<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .box {
            display: flex;
            /* justify-content: center; */
            /* align-items: center; */

            /* 主轴的方向是  */
            /* flex-direction: column; */
            /* justify-content: space-between;
            align-items: center; */
            width: 800px;
            height: 500px;
            margin: 100px auto;
            background-color: skyblue;
            /* border-radius: 10px; */
        }

        .yuan {
            flex: 1;
            background-color: pink;
            : 
            /* width: 10px;
            height: 10px;
            background-color: black;
            border-radius: 50%; */
            /* margin: 0 10px; */
        }
    </style>
</head>

<body>
    <div class="box">
        <div class="yuan">1</div>
        <div class="yuan">2</div>
        <div class="yuan">3</div>
        <div class="yuan">2</div>
        <div class="yuan">3</div>
        <div class="yuan">2</div>
        <div class="yuan">3</div>
    </div>
</body>

</html>